In recent years, sequential-motion exposure apparatus such as the following have mainly been used in lithography processes for the manufacture of semiconductor devices, liquid-crystal-display elements, and the like, with increasingly greater integration of semiconductors and the like: step-and-repeat type reduction projection-exposure apparatus (so-called “steppers”), and step-and-scan type scanning projection-exposure apparatus (so-called “scanning steppers” or “scanners”). These exposure apparatus make possible the formation of fine patterns on a photosensitive body with good accuracy and high throughput.
In these types of exposure apparatus, a wafer stage is used as a movable-body apparatus for moving a photosensitive body (hereinafter “wafer”) such as a wafer, glass plate, or the like. The wafer stage comprises a rough stage, which is driven within a two-dimensional (X-Y) plane using a biaxial linear motor, planar motor, or the like, and a fine stage that supports the wafer on the rough stage and is driven finely in the Z-axis direction, in an inclined direction, or the like, using a voice-coil motor or the like.
In these movable-body apparatus, the actuators (linear motor, planar motor, voice-coil motor, or the like) comprise an armature unit comprising a plurality of coils and a magnet unit comprising a plurality of magnets. The coils emit heat due to electric current being supplied to the coils of the armature unit. To suppress adverse influences of this heat on exposure accuracy, a conduit is conventionally connected to part of the wafer stage, and coolant is circulated through the conduit to the vicinity of the heat-producing portion of the wafer stage. Unfortunately, since the coolant conduit must be pulled along with movements of the stage, the controllability of wafer positioning is reduced, which reduces exposure accuracy.
Also, a conventional wafer stage has wiring or the like connected to it to supply electrical current to the actuator(s). This wiring also must be, similar to the coolant conduit, pulled along with motions of the stage. This need to pull and carry the wiring also is a cause of reduced controllability of wafer positioning.